Altica carinthiaca: moving with climate change, or simply overlooked?

Altica carinthiaca Weise 1888 is a small (3-4mm) leaf beetle (Coleoptera: Chrysomelidae) widespread but scattered the western Palaearctic from Britain to Baikal, mainly in northern European countries; in more southerly locations it is associated with montane and submontane habitats. It was only recognised as a British species in 2000 (Cox 2000) having been confused with A. palustris and A. pusilla var. montana, although re-examination of collections has found British specimens dating back to 1939. An excellent photograph of a male, including aedeagus, can be found here.

Although not considered threatened in Britain, it is generally considered rare across its range as a whole although known from a range of habitats. The British host plant is the Meadow Vetchling Lathyrus pratensis, while in continental Europe it is also known from other plants such as Knotgrass Polygonum aviculare, Salad Burnet Sanguisorba minor and Speedwells Veronica sp. (Borowiec & Scibior 2008).

Following re-evaluation of old specimens, a British distribution map could be created which, as in Cox (2007), indicates a southern and eastern English distribution.

However, in February 2011, the species was discovered during suction-sampling in Cheshire, well north of its accepted distribution (see the red cross on the map). In recent years it has also increased its range in Finland (Kangas & Rutanen 1993), and been found for the first time in Poland (Borowiec & Scibior 2008).

In Poland, the previous lack of records could simply be due to the species having been overlooked, and the authors consider this to be the case due to previous problems with identification. However, although this has clearly also occurred elsewhere (e.g. Britain), a genuine change in distribution can not be discounted. As a species associated with higher latitudes (or higher altitudes at lower latitudes), it is certainly a species which might be expected to have its range affected by the increasing temperatures caused by climate change. The difficulty is of course that any perceived northerly (or higher-altitude) shift in distribution could be due to the species having been previously overlooked in these areas - without a well understood 'initial' distribution it is difficult to isolate temperature/climate effects. However, the re-evaluation of British specimens did not find any more northerly locations, so the map above (current in 2007 apart from the Cheshire record) may well be an accurate representation of the species' British range at that time. So, what does the Cheshire record tell us? Well, apart from the fact that A. carinthiaca is now present in Cheshire, not necessarily much - it is after all only one record - but if other northerly locations are found, it may reveal a shift in the species' northern boundary. Certainly, with taxonomic and identification problems now having been tackled (at least to some extent), it is hoped that more records of this species will appear so that changes in range, if any, can be identified as has been the case with more 'charismatic' species such as the Long-winged Conehead Conocephalus discolor and the Wasp Spider Argiope bruennichi which have expanded their ranges in Britain, while montane/high-latitude species such as the Ptarmigan Lagopus mutus appear to be being squeezed out as their range disappears. As for A. carinthiaca, and many other species, time, and hopefully good data, will tell.

References

Borowiec, L., & Scibior, R. (2008). Altica carinthiaca (WEISE, 1888) (Coleoptera, Chrysomelidae) - species
new to the Polish fauna. Polish Journal of Entomology, 77 (4), 305-308 Other: ark:/13960/t56d64f8s

Cox, M.L. (2000). Progress report on the Bruchidae/Chrysomelidae Recording Scheme. The Coleopterist 9(2): 65-74.

Cox, M.L. (2007). Atlas of the Seed and Leaf Beetles of Britain and Ireland. Pisces, Newbury.

Kangas, E. & Rutanen, I. (1993). Identification of females of the Finnish species of Altica Müller (Coleoptera, Chrysomelidae). Entomologica Fennica 4: 115-129.